diff --git a/Classes/PHPExcel/Calculation.php b/Classes/PHPExcel/Calculation.php
index 385d1920..2fc63e58 100644
--- a/Classes/PHPExcel/Calculation.php
+++ b/Classes/PHPExcel/Calculation.php
@@ -2977,7 +2977,7 @@ class PHPExcel_Calculation {
 		}
 
 		while (($op = $stack->pop()) !== NULL) {	// pop everything off the stack and push onto output
-			if ((is_array($opCharacter) && $opCharacter['value'] == '(') || ($opCharacter === '('))
+			if ((is_array($op) && $op['value'] == '(') || ($op === '('))
 				return $this->_raiseFormulaError("Formula Error: Expecting ')'");	// if there are any opening braces on the stack, then braces were unbalanced
 			$output[] = $op;
 		}
diff --git a/changelog.txt b/changelog.txt
index 1c4733dc..de9b0cfd 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -72,6 +72,9 @@ The following methods will be changed in version 1.7.9
 
 
 Fixed in develop branch:
+
+
+2012-10-12 (v1.7.8):
 - Special:  (kkamkou)    Phar builder script to add phar file as a distribution option
 - Feature:  (MBaker)     Refactor PDF Writer to allow use with a choice of PDF Rendering library
                          rather than restricting to tcPDF